Sensor Device

Abstract

To obtain high resolution of an acceleration sensor.SOLUTION: A sensor device is provided that includes: a plurality of acceleration sensors provided on an object and within a predetermined distance from each other and detecting acceleration of the object; a distribution calculation unit for calculating distribution of acceleration of the object that is distribution of a plurality of acceleration detected by the plurality of acceleration sensors: and a resolution calculation unit for calculating resolution of the plurality of acceleration sensors based on the distribution of the plurality of acceleration calculated by the distribution calculation unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sensor device. [Background technology]

[0002] Patent Document 1 states that "the present invention is an acceleration sensor equipped with an AD converter that achieves both a wide dynamic range and high output resolution" (paragraph 0006). [Prior art document] [Patent documents] [Patent Document 1] International Publication No. 2015 / 052926 Summary of the Invention [Problem to be solved by the invention]

[0003] It is preferable that the acceleration sensor has a high resolution. [Means for solving the problem]

[0004] In a first aspect of the present invention, there is provided a sensor device comprising: a plurality of acceleration sensors that are provided on an object and are located within a predetermined distance from each other and detect acceleration of the object, a distribution calculation unit that calculates a distribution of the accelerations of the object, which is a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, and a resolution calculation unit that calculates a resolution of the plurality of acceleration sensors based on the distribution of the plurality of accelerations calculated by the distribution calculation unit.

[0005] Each of the multiple acceleration sensors may have a movable electrode and fixed electrodes arranged adjacent to one side and the other side of the movable electrode in a predetermined direction. A direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in a first acceleration sensor of the multiple acceleration sensors may be the same as a direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in a second acceleration sensor of the multiple acceleration sensors.

[0006] The first acceleration sensor may detect a first acceleration of the object at each of the multiple times. The second acceleration sensor may detect a second acceleration of the object at each of the multiple times. The distribution calculation unit may calculate a distribution of the acceleration of the object based on the first acceleration and the second acceleration at each of the multiple times.

[0007] The distribution calculation unit may calculate an approximation line representing a relationship between the first acceleration and the second acceleration over multiple times, calculate at least one of an approximate first acceleration in which the first acceleration is approximated and an approximate second acceleration in which the second acceleration is approximated based on the approximation line, and calculate a distribution of the acceleration of the object based on at least one of a first difference between the approximate first acceleration and the second acceleration and a second difference between the approximate second acceleration and the first acceleration.

[0008] The distribution calculation unit may calculate a distribution of the acceleration of the object based on at least one of a plurality of first differences, which are first differences between the approximate first acceleration and the second acceleration at each of the plurality of times, and a plurality of second differences, which are second differences between the approximate second acceleration and the first acceleration at each of the plurality of times.

[0009] The resolution calculation section may calculate the resolution of the second acceleration sensor based on the maximum value of the plurality of first differences.

[0010] The resolution calculation section may calculate the resolution of the first acceleration sensor based on the maximum value of the plurality of second differences.

[0011] The resolution calculation section may calculate the resolution of the acceleration sensor based on a standard deviation of the plurality of first differences.

[0012] The resolution calculation section may calculate the resolution of the acceleration sensor based on a standard deviation of the plurality of second differences.

[0013] The distribution calculation section may calculate a distribution of the acceleration of the object based on a third difference which is a difference between the first acceleration and the second acceleration.

[0014] The distribution calculation section may calculate a distribution of the acceleration of the object based on a plurality of third differences, which are third differences between the first acceleration and the second acceleration at each of a plurality of times.

[0015] The resolution calculation section may calculate the resolution of the first acceleration sensor and the second acceleration sensor based on the maximum value of the plurality of third differences.

[0016] The resolution calculation section may calculate the resolution of the first acceleration sensor and the second acceleration sensor based on a standard deviation of the plurality of third differences.

[0017] A third acceleration sensor of the multiple acceleration sensors may detect a third acceleration of the object at each of the multiple times. The distribution calculation unit may calculate a first distribution of acceleration of the object based on the first acceleration and the second acceleration, calculate a second distribution of acceleration of the object based on the second acceleration and the third acceleration, and calculate a third distribution of acceleration of the object based on the third acceleration and the first acceleration, at each of the multiple times. The resolution calculation unit may calculate resolutions of the first acceleration sensor, the second acceleration sensor, and the third acceleration sensor based on the first distribution, the second distribution, and the third distribution.

[0018] The first acceleration sensor may detect a first acceleration of the object at each of a plurality of times based on a first time. The second acceleration sensor may detect a second acceleration of the object at each of a plurality of times based on one or more second times different from the first time. The distribution calculation unit may calculate a distribution of the acceleration of the object based on the first acceleration at each of the plurality of times based on the first time and the second acceleration at each of the plurality of times based on the second time.

[0019] The distribution calculation section may calculate a plurality of distributions of the acceleration of the object based on the first acceleration at each of a plurality of times based on the first time and the second acceleration at each of a plurality of times based on the second times. The resolution calculation section may calculate the resolution of the first acceleration sensor and the second acceleration sensor based on the plurality of distributions.

[0020] The resolution calculation section may calculate the minimum resolution of the first acceleration sensor and the second acceleration sensor based on the plurality of distributions.

[0021] The above summary of the invention does not list all of the features of the present invention. Also, subcombinations of these features may also be inventions. [Brief description of the drawings]

[0022] [Figure 1] FIG. 3 illustrates an example of a resolution measurement system 300 according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing an example of a block diagram of a sensor unit 200 shown in FIG. [Diagram 3] 3 is a diagram showing an example of details of the acceleration sensor 10 shown in FIG. 2. FIG. [Figure 4] 4 is a diagram showing an example of an AA' cross section of the acceleration sensor 10 shown in FIG. [Diagram 5] FIG. 1 is a diagram showing an example of a block diagram of a sensor device 100. [Figure 6] 11 is a diagram showing the distribution of a first acceleration Ax1 and a second acceleration Ax2 detected over a plurality of times. FIG. [Figure 7] 11 is a diagram showing the distribution of a first acceleration Ay1 and a second acceleration Ay2 detected over a plurality of times. FIG. [Figure 8] 11 is a diagram showing the distribution of a first acceleration Az1 and a second acceleration Az2 detected over a plurality of times. FIG. [Figure 9] 1 is a conceptual diagram showing an example of a method for calculating the distribution of acceleration A. FIG. [Figure 10]13 is a conceptual diagram showing another example of a method for calculating the distribution of acceleration A. FIG. [Figure 11] FIG. 13 is a diagram showing an example of a distribution of a plurality of first differences dx1 across a plurality of times. [Figure 12] FIG. 13 is a diagram showing an example of a distribution of a plurality of first differences dy1 across a plurality of times. [Figure 13] 13 is a diagram showing an example of a distribution of a plurality of first differences dz1 across a plurality of times. FIG. [Figure 14] FIG. 13 is a diagram illustrating an example of the relationship between time t and resolution Rx. [Figure 15] FIG. 13 is a diagram illustrating an example of a relationship between time t and standard deviation σx. [Figure 16] FIG. 11 is a diagram illustrating an example of a relationship between time t and resolution Ry. [Figure 17] FIG. 13 is a diagram illustrating an example of a relationship between time t and standard deviation σy. [Figure 18] FIG. 11 is a diagram showing an example of the relationship between time t and resolution Rz. [Figure 19] FIG. 13 is a diagram illustrating an example of the relationship between time t and standard deviation σz. [Figure 20] 13 is a conceptual diagram showing another example of a method for calculating the distribution of acceleration A. FIG. [Figure 21] FIG. 13 is a diagram showing an example of a distribution of a plurality of third differences dx3 across a plurality of times. [Figure 22] FIG. 13 is a diagram showing an example of a distribution of a plurality of third differences dy3 across a plurality of times. [Figure 23] 13 is a diagram showing an example of a distribution of a plurality of third differences dz3 across a plurality of times. FIG. [Figure 24] 1 is a conceptual diagram showing timing at which each of a plurality of acceleration sensors 10 according to an embodiment of the present invention detects an acceleration A. FIG. [Diagram 25] FIG. 11 is a conceptual diagram showing a plurality of second times tc2. [Figure 26] 1 is a diagram showing an example of the relationship between the distribution of acceleration A and resolution R. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0024] Fig. 1 is a diagram showing an example of a resolution measurement system 300 according to an embodiment of the present invention. The resolution measurement system 300 includes a sensor device 100 and an NTP server 140. In Fig. 1, the range of the sensor device 100 is indicated by a fine dashed line. The sensor device 100 of this example includes a plurality of sensor units 200 and a computer 110. In this example, the sensor device 100 includes four sensor units 200 (sensor unit 200-1 to sensor unit 200-4).

[0025] The sensor unit 200 is provided on the object 210. The sensor unit 200 includes an acceleration sensor 10 (described later). The acceleration sensor 10 detects the acceleration of the object 210. The acceleration of the object 210 refers to the acceleration of the object 210 caused by vibration of the object 210 or the like.

[0026] The object 210 is, for example, a floor of a building. A building is a structure fixed on a piece of land and used for purposes such as residence, office, store, factory, warehouse, etc. In FIG. 1, a part of the object 210 is shown. The sensor unit 200 may be provided in the object 210.

[0027] The multiple acceleration sensors 10 are disposed within a predetermined distance from each other. The predetermined distance is defined as distance d. Acceleration is detected at the same location on the object 210. Distance d is a distance at which the multiple acceleration sensors 10 can be considered to be detecting acceleration at the same location on the object 210. Distance d is a distance at which the difference in acceleration of the object 210 detected by the multiple acceleration sensors 10 becomes negligibly small. Distance d may be 0.05 m or more and 0.3 m or less, or 0.05 m or more and 0.15 m or less.

[0028] The resolution measurement system 300 may include a power supply hub 130. The power supply hub 130 is an interface that communicates with the sensor section 200 and supplies power to the sensor section 200. The power supply hub 130 may be a so-called Power over Ethernet (PoE) hub.

[0029] The NTP server 140 is a server that distributes atomic clock time, which is time adjusted to be synchronized with Coordinated Universal Time.

[0030] The resolution measurement system 300 may include a communication line 150. The communication line 150 is connected to the computer 110, the NTP server 140, the power supply hub 130, and the sensor section 200. In this example, the computer 110, the NTP server 140, the power supply hub 130, and the sensor section 200 communicate with each other through the communication line 150. The communication line 150 is, for example, a LAN cable.

[0031] Fig. 2 is a diagram showing an example of a block diagram of the sensor unit 200 shown in Fig. 1. Fig. 2 is an example of a block diagram of one of the sensor units 200-1 to 200-4 shown in Fig. 1. In Fig. 2, the range of the sensor unit 200 is indicated by a rough dashed line.

[0032] Sensor device 100 (see FIG. 1) includes a plurality of acceleration sensors 10. Acceleration sensors 10 are provided on an object 210. Acceleration sensors 10 detect the acceleration of object 210. In this example, sensor unit 200 includes acceleration sensors 10. Sensor units 200-1 to 200-4 (see FIG. 1) each include an acceleration sensor 10.

[0033] The sensor unit 200 further includes a frequency oscillator 20 and a sensor control unit 30. The frequency oscillator 20 generates a clock signal with a period T. The clock signal is referred to as a clock signal CK. The frequency oscillators 20 in the multiple sensor units 200 generate clock signals CK synchronized with each other. In this example, the acceleration sensor 10 detects the acceleration of the object 210 at a time based on the clock signal CK. The time based on the clock signal CK is, for example, the time when the clock signal CK rises.

[0034] A voltage may be supplied to the variable frequency oscillator 20 by a power supply hub 130. The sensor control unit 30 controls signal processing in the sensor device 100. The sensor control unit 30 may be a so-called CPU (Central Processing Unit).

[0035] The sensor device 100 may include a storage unit 70. The storage unit 70 may store the acceleration data detected by the acceleration sensor 10.

[0036] The sensor device 100 may include an analog signal processor 50, an LPF (low pass filter) 52, and an AD converter (analog-digital converter) 54. In this example, the analog signal processor 50 converts changes in capacitance between a fixed electrode 21 (described later), a fixed electrode 22 (described later), and a fixed electrode 26 (described later) and a movable electrode 23 (described later) detected by the acceleration sensor 10 into a voltage signal. The LPF 52 removes high frequency noise from the voltage signal output from the analog signal processor 50.

[0037] The AD converter 54 converts the analog voltage signal, from which high-frequency noise has been removed by the LPF 52, into a digital signal at the timing of the clock signal CK. The sensor control unit 30 may transmit an AD conversion start signal to the AD converter 54 to start analog-to-digital conversion. The AD conversion start signal may be generated based on a predetermined reference time. The AD converter 54 may start analog-to-digital conversion at the timing of receiving the AD conversion start signal.

[0038] The sensor device 100 may include an interface unit 58. The interface unit 58 may receive power supplied by the power supply hub 130. The interface unit 58 may mediate communication between the power supply hub 130 and the sensor control unit 30.

[0039] Fig. 3 is a diagram showing an example of the details of the acceleration sensor 10 shown in Fig. 2. The acceleration sensor 10 of this example is a capacitance-type MEMS acceleration sensor. The acceleration sensor 10 has a fixed electrode 21, a fixed electrode 22, a movable electrode 23, a fixed frame 24, and an elastic part 25. The movable electrode 23 may be a plate-shaped member.

[0040] In this specification, technical matters may be explained using orthogonal coordinate axes of the X-axis, Y-axis, and Z-axis. In this specification, a plane parallel to the plate surface of the movable electrode 23 is defined as the XY plane. In this specification, a direction perpendicular to the plate surface of the movable electrode 23 is defined as the Z-axis direction. In this specification, a predetermined direction in the XY plane is defined as the X-axis direction, and a direction perpendicular to the X-axis in the XY plane is defined as the Y-axis direction.

[0041] In this specification, the X-axis direction refers to a direction from one side to the other side in a direction parallel to the X-axis, and a direction from the other side to one side. That is, in this specification, the X-axis direction does not refer to either one of the two directions parallel to the X-axis, but refers to a direction parallel to the X-axis. In this specification, the same applies to the Y-axis and Z-axis directions. The Z-axis direction may be parallel to the direction of gravity. When the Z-axis direction is parallel to the direction of gravity, the XY plane may be a horizontal plane.

[0042] The acceleration sensor 10 of this example has two fixed electrodes 21 (fixed electrode 21-1 and fixed electrode 21-2). In this example, the fixed electrode 21-1 is disposed adjacent to one side of the movable electrode 23 in a predetermined direction (the X-axis direction in this example), and the fixed electrode 21-2 is disposed adjacent to the other side of the movable electrode 23 in the X-axis direction. A gap is provided between the fixed electrode 21 and the movable electrode 23 in the X-axis direction. That is, the fixed electrode 21 and the movable electrode 23 are not in contact with each other.

[0043] The acceleration sensor 10 of this example has two fixed electrodes 22 (fixed electrode 22-1 and fixed electrode 22-2). In this example, the fixed electrode 22-1 is disposed adjacent to one side of the movable electrode 23 in a predetermined direction (the Y-axis direction in this example), and the fixed electrode 22-2 is disposed adjacent to the other side of the movable electrode 23 in the Y-axis direction. A gap is provided between the fixed electrode 22 and the movable electrode 23 in the Y-axis direction. That is, the fixed electrode 22 and the movable electrode 23 are not in contact with each other.

[0044] The fixed frame 24 may be provided so as to surround the fixed electrodes 21, 22, the movable electrode 23, and the elastic portion 25 in the XY plane. In this example, the fixed electrodes 21 and 22 are fixed to the fixed frame 24. In this example, one end of the elastic portion 25 is fixed to the fixed frame 24, and the other end of the elastic portion 25 is fixed to the movable electrode 23.

[0045] The acceleration sensor 10 may have a charge amplifier 92. The acceleration sensor 10 may have a plurality of charge amplifiers 92. The acceleration sensor 10 of this example has five charge amplifiers 92 (charge amplifier 92-1 to charge amplifier 92-5). The charge amplifier 92-5 will be described later.

[0046] The acceleration sensor 10 may include a voltage application section 90. The voltage application section 90 applies a bias voltage to the elastic section 25.

[0047] In this example, charge amplifiers 92-1 to 92-4 are electrically connected to fixed electrode 21-1, fixed electrode 22-2, fixed electrode 21-2, and fixed electrode 22-1, respectively.

[0048] The movable electrode 23 is displaced by acceleration. The acceleration sensor 10 of this example detects a change in capacitance between the movable electrode 23 and the fixed electrodes 21, 22, and 26 (described later) due to the displacement of the movable electrode 23. The change in capacitance may be amplified by the charge amplifiers 92-1 to 92-4. When the acceleration sensor 10 detects the change in capacitance, a bias voltage may be applied to the elastic portion 25 by the voltage application unit 90. The acceleration sensor 10 of this example detects the acceleration by detecting the change in capacitance. The acceleration sensor 10 of this example detects the component of acceleration in the X-axis direction by detecting the change in capacitance between the fixed electrode 21 and the movable electrode 23. The acceleration sensor 10 of this example detects the component of acceleration in the Y-axis direction by detecting the change in capacitance between the fixed electrode 22 and the movable electrode 23.

[0049] When the sensor unit 200 (see FIG. 1) is provided on the floor of the object 210 (see FIG. 1), the sensor unit 200 may be placed on the floor such that the plate surface (in this example, the XY plane) of the movable electrode 23 of the acceleration sensor 10 is parallel to the surface of the floor of the object 210.

[0050] Fig. 4 is a diagram showing an example of an AA' cross section of the acceleration sensor 10 shown in Fig. 3. The AA' line is an XZ cross section passing through the fixed frame 24, the fixed electrode 21-1, the movable electrode 23, and the fixed electrode 21-2.

[0051] The acceleration sensor 10 of this example further includes a fixed electrode 26. The fixed electrode 26 may be disposed adjacent to one side of the movable electrode 23 in the Z-axis direction. Spaces 27 are provided on both sides of the movable electrode 23 in the Z-axis direction. The space 27-1 is provided between the movable electrode 23 and the fixed electrode 26 in the Z-axis direction. In other words, the movable electrode 23 and the fixed electrode 26 are not in contact with each other. The space 27-2 is provided on the opposite side of the space 27-1 in the Z-axis direction with respect to the movable electrode 23.

[0052] In this example, the charge amplifier 92-5 is electrically connected to the fixed electrode 26. A change in capacitance between the movable electrode 23 and the fixed electrode 26 caused by the displacement of the movable electrode 23 may be amplified by the charge amplifier 92-5. The acceleration sensor 10 of this example detects the change in capacitance between the fixed electrode 26 and the movable electrode 23, thereby detecting the Z-axis component of the acceleration.

[0053] Fig. 5 is a diagram showing an example of a block diagram of the sensor device 100. The power supply hub 130 and the NTP server 140 shown in Fig. 1 are omitted in Fig. 5. The frequency oscillator 20, the analog signal processing unit 50, the LPF 52, the AD converter 54, the interface unit 58, and the storage unit 70 shown in Fig. 2 are omitted in Fig. 5.

[0054] The sensor device 100 includes a distribution calculation unit 15 and a resolution calculation unit 17. In this example, a computer 110 includes the distribution calculation unit 15 and the resolution calculation unit 17. The computer 110 includes a control unit 16. The control unit 16 controls the calculations in the distribution calculation unit 15 and the resolution calculation unit 17. The control unit 16 may be a so-called CPU (Central Processing Unit).

[0055] The acceleration sensors 10 of sensor units 200-1 to 200-4 are referred to as a first acceleration sensor 11, a second acceleration sensor 12, a third acceleration sensor 13, and a fourth acceleration sensor 14, respectively. The distribution calculation unit 15 calculates the distribution of a plurality of accelerations detected by the plurality of acceleration sensors 10. The accelerations in question are the accelerations of an object 210 (see FIG. 1). The distribution of a plurality of accelerations refers to the distribution of accelerations detected by at least two of the first acceleration sensor 11 to the fourth acceleration sensor 14.

[0056] The resolution calculation section 17 calculates the resolution of the acceleration sensor 10 based on the distribution of the multiple accelerations calculated by the distribution calculation section 15. The resolution calculation section 17 may calculate the resolution of the multiple acceleration sensors 10 based on the distribution of the multiple accelerations. In this specification, the resolution of the acceleration sensor 10 refers to the minimum value of acceleration that the acceleration sensor 10 can detect. The resolution of the acceleration sensor 10 is defined as resolution R.

[0057] When measuring the resolution R of one acceleration sensor 10, it is desirable that the acceleration of the object 210 be as small as possible so that the acceleration sensor 10 can detect a small acceleration. The small acceleration of the object 210 may be an acceleration of a magnitude that is difficult for a human to feel. For this reason, when the acceleration sensor 10 is capable of detecting a small acceleration, it is desirable that the acceleration sensor 10 is provided on the object 210 that is installed, for example, deep in the mountains, where the acceleration is likely to be maintained at a small acceleration. For this reason, when the acceleration sensor 10 is capable of detecting a small acceleration, it may be difficult to measure the resolution R of one acceleration sensor 10.

[0058] In the sensor device 100, the resolution calculation unit 17 calculates the resolution R of the multiple acceleration sensors 10 based on the distribution of the multiple accelerations calculated by the distribution calculation unit 15. Therefore, even if one acceleration sensor 10 is capable of detecting the above-mentioned minute acceleration, the resolution R of the acceleration sensor 10 can be easily calculated regardless of the acceleration state at the location where the target object 210 is provided.

[0059] The direction from the fixed electrode 21-1 to the fixed electrode 21-2 in the first acceleration sensor 11 of the sensor unit 200-1 may be the same as the direction from the fixed electrode 21-1 to the fixed electrode 21-2 in the second acceleration sensor 12 of the sensor unit 200-2. The direction being the same may mean that the direction from the fixed electrode 21-1 to the fixed electrode 21-2 in the first acceleration sensor 11 is parallel to the direction from the fixed electrode 21-1 to the fixed electrode 21-2 in the second acceleration sensor 12. This makes it easier for the resolution calculation unit 17 to calculate the resolution R of the multiple acceleration sensors 10. Similarly, the direction from the fixed electrode 22-1 to the fixed electrode 22-2 in the first acceleration sensor 11 of the sensor unit 200-1 may be the same as the direction from the fixed electrode 22-1 to the fixed electrode 22-2 in the second acceleration sensor 12 of the sensor unit 200-2.

[0060] The acceleration detected by the acceleration sensor 10 is defined as acceleration A. The acceleration detected by the first acceleration sensor 11 is defined as first acceleration A1. The acceleration detected by the second acceleration sensor 12 is defined as second acceleration A2. The acceleration detected by the third acceleration sensor 13 is defined as third acceleration A3. The acceleration detected by the fourth acceleration sensor 14 is defined as fourth acceleration A4.

[0061] The first acceleration sensor 11 may detect a first acceleration A1 of the object 210 at each of a plurality of times. The second acceleration sensor 12 may detect a second acceleration A2 of the object 210 at each of a plurality of times. The third acceleration sensor 13 may detect a third acceleration A3 of the object 210 at each of a plurality of times. The fourth acceleration sensor 14 may detect a fourth acceleration A4 of the object 210 at each of a plurality of times. The plurality of times are times based on a clock signal CK. Since the frequency oscillators 20 in the plurality of sensor units 200 generate clock signals CK synchronized with each other, the first acceleration A1 to the fourth acceleration A4 are detected at the same time.

[0062] The X-axis component, the Y-axis component, and the Z-axis component of the first acceleration A1 are respectively the first acceleration Ax1, the first acceleration Ay1, and the first acceleration Az1. The X-axis component, the Y-axis component, and the Z-axis component of the second acceleration A2 are respectively the second acceleration Ax2, the second acceleration Ay2, and the second acceleration Az2. The X-axis component, the Y-axis component, and the Z-axis component of the third acceleration A3 are respectively the third acceleration Ax3, the third acceleration Ay3, and the third acceleration Az3. The X-axis component, the Y-axis component, and the Z-axis component of the fourth acceleration A4 are respectively the fourth acceleration Ax4, the fourth acceleration Ay4, and the fourth acceleration Az4.

[0063] FIG. 6 is a diagram showing the distribution of the first acceleration Ax1 and the second acceleration Ax2 detected over a plurality of times. FIG. 7 is a diagram showing the distribution of the first acceleration Ay1 and the second acceleration Ay2 detected over a plurality of times. FIG. 8 is a diagram showing the distribution of the first acceleration Az1 and the second acceleration Az2 detected over a plurality of times. In FIG. 6, one of the first acceleration Ax1 and the second acceleration Ax2 detected over a plurality of times is plotted on one axis, and the other is plotted on the other axis. The same is true in FIG. 7 and FIG. 8.

[0064] 6 to 8 are examples of plotting 4000 pieces of data detected over 20 seconds at a period T of 5 ms. Each diamond plot corresponds to one piece of data. In FIG. 6, the first acceleration Ax1 and the second acceleration Ax2 are each distributed within the acceleration range of the object 210. In FIG. 7, the first acceleration Ay1 and the second acceleration Ay2 are each distributed within the acceleration range of the object 210. In FIG. 8, the first acceleration Az1 and the second acceleration Az2 are each distributed within the acceleration range of the object 210.

[0065] The multiple acceleration sensors 10 detect the acceleration of the same location on the object 210 at the same time. Therefore, the first acceleration Ax1 and the second acceleration Ax2 ideally coincide with each other. Therefore, the data of the first acceleration Ax1 and the data of the second acceleration Ax2 detected over multiple times are ideally plotted on a straight line of Ax2=Ax1 in FIG. 6. However, due to individual differences between the first acceleration sensor 11 and the second acceleration sensor 12, the data of the first acceleration Ax1 and the data of the second acceleration Ax2 are actually distributed near the straight line of Ax2=Ax1. Similarly, the data of the first acceleration Ay1 and the data of the second acceleration Ay2 are distributed near the straight line of Ay2=Ay1 in FIG. 7. Similarly, the data of the first acceleration Az1 and the data of the second acceleration Az2 are distributed near the straight line of Az2=Az1 in FIG. 8.

[0066] The distribution calculation section 15 (see FIG. 5) may calculate the distribution of the acceleration A of the object 210 based on the first acceleration A1 and the second acceleration A2 at each of the multiple times. In this example, the distribution calculation section 15 calculates the distribution of the X component of the acceleration A based on the first acceleration Ax1 and the second acceleration Ax2, calculates the distribution of the Y component of the acceleration A based on the first acceleration Ay1 and the second acceleration Ay2, and calculates the distribution of the Z component of the acceleration A based on the first acceleration Az1 and the second acceleration Az2, at each of the multiple times.

[0067] In Fig. 6, the approximation line Lx represents the relationship between the first acceleration Ax1 and the second acceleration Ax2 over a plurality of times. In Fig. 7, the approximation line Ly represents the relationship between the first acceleration Ay1 and the second acceleration Ay2 over a plurality of times. In Fig. 8, the approximation line Lz represents the relationship between the first acceleration Az1 and the second acceleration Az2 over a plurality of times.

[0068] The distribution calculation section 15 (see FIG. 5) may calculate the approximation line Lx. The distribution calculation section 15 calculating the approximation line Lx means that the distribution calculation section 15 calculates an approximation equation (a linear equation in the example of FIG. 6) between the first acceleration Ax1 and the second acceleration Ax2 based on the relationship between the first acceleration Ax1 and the second acceleration Ax2 over a plurality of times. The distribution calculation section 15 may calculate at least one of the approximation line Lx, the approximation line Ly, and the approximation line Lz.

[0069] The relationship between the first acceleration Ax1 and the second acceleration Ax2 over a plurality of times may be approximated by a linear function. When the relationship is approximated by a linear function, the distribution calculation unit 15 (see FIG. 5) may calculate the approximation line Lx, the approximation line Ly, and the approximation line Lz by the least squares method. The relationship between the first acceleration Ax1 and the second acceleration Ax2 over a plurality of times may be approximated by a quadratic or higher function. The same is true for the relationship between the first acceleration Ay1 and the second acceleration Ay2, and the relationship between the first acceleration Az1 and the second acceleration Az2. In this example, the relationship between the first acceleration Ax1 and the second acceleration Ax2 over a plurality of times is approximated by a linear function with a slope α and an intercept β. In this example, the relationship between the first acceleration Ay1 and the second acceleration Ay2 over a plurality of times is approximated by a linear function with a slope α' and an intercept β'. In this example, the relationship between the first acceleration Az1 and the second acceleration Az2 over a plurality of times is approximated by a one-time function with a slope α″ and an intercept β″.

[0070] FIG. 9 is a conceptual diagram showing an example of a method for calculating the distribution of the acceleration A. The acceleration obtained by approximating the first acceleration Ax1 is set as the approximate first acceleration Ax1'. The distribution calculation unit 15 (see FIG. 5) may calculate the approximate first acceleration Ax1' based on the approximation line Lx. In this example, the first acceleration Ax1 at an arbitrary time t1 is set as the acceleration ax1-1. In this example, the approximate first acceleration Ax1' calculated based on the approximation line Lx and approximating the acceleration ax1-1 is set as the approximate first acceleration ax1-1'. In this example, the approximate first acceleration ax1-1' is calculated by substituting the acceleration ax1-1 for Ax1 in the equation of the linear function of the approximation line Lx. The approximate first acceleration ax1-1' may be calculated by the distribution calculation unit 15 (see FIG. 5).

[0071] The second acceleration Ax2 at time t1 is defined as acceleration ax2-2. The difference between the approximate first acceleration ax1-1' and the acceleration ax2-2 is defined as a first difference dx1. The distribution calculation unit 15 may calculate the first difference dx1. In FIG. 9, the first difference dx1 is indicated by a double-headed arrow.

[0072] The distribution calculation section 15 (see FIG. 5) may calculate the distribution of the acceleration A of the object 210 (see FIG. 1) based on the first difference dx1. The distribution calculation section 15 may calculate the distribution of the X-axis direction component of the acceleration A of the object 210 (see FIG. 1) based on the first difference dx1.

[0073] The distribution calculation section 15 (see FIG. 5) may calculate a distribution of the acceleration A of the object 210 based on a plurality of first differences dx1, which are first differences dx1 between the approximate first acceleration Ax1' and the second acceleration Ax2 at each of a plurality of times. The plurality of times refers to 4000 times in the example of FIG. 6. The distribution calculation section 15 may calculate a distribution of the acceleration A of the object 210 in the X-axis direction based on the plurality of first differences dx1. The plurality of first differences dx1 refers to 4000 first differences dx1 in the example of FIG. 6.

[0074] The distribution calculation section 15 (see FIG. 5) may similarly calculate a first difference dy1 for the first acceleration Ay1 and the second acceleration Ay2 in the Y-axis direction, and may similarly calculate a first difference dz1 for the first acceleration Az1 and the second acceleration Az2 in the Z-axis direction. The distribution calculation section 15 may similarly calculate the distribution of the acceleration A of the object 210 based on a plurality of first differences dy1, and may calculate the distribution of the acceleration A of the object 210 based on a plurality of first differences dz1.

[0075] FIG. 10 is a conceptual diagram showing another example of a method for calculating the distribution of the acceleration A. The acceleration obtained by approximating the second acceleration Ax2 is set as the approximate second acceleration Ax2'. The distribution calculation unit 15 (see FIG. 5) may calculate the approximate second acceleration Ax2' based on the approximation line Lx. In this example, the second acceleration Ax2 at an arbitrary time t1' is set as the acceleration ax2-1. In this example, the approximate second acceleration Ax2' calculated based on the approximation line Lx and approximating the acceleration ax2-1 is set as the approximate second acceleration ax2-1'. In this example, the approximate second acceleration ax2-1' is calculated by substituting the acceleration ax2-1 for Ax2 in the equation of the linear function of the approximation line Lx. The approximate second acceleration ax2-1' may be calculated by the distribution calculation unit 15 (see FIG. 5).

[0076] The first acceleration Ax1 at time t1' is defined as acceleration ax1-2. The difference between the approximate second acceleration ax2-1' and the acceleration ax1-2 is defined as a second difference dx2. In FIG 10, the second difference dx2 is indicated by a double-headed arrow.

[0077] The distribution calculation section 15 (see FIG. 5) may calculate the distribution of the acceleration A of the object 210 (see FIG. 1) based on the second difference dx2. The distribution calculation section 15 may calculate the distribution of the X-axis direction component of the acceleration A of the object 210 (see FIG. 1) based on the second difference dx2.

[0078] The distribution calculation section 15 may calculate a distribution of the acceleration A of the object 210 based on a plurality of second differences dx2 between the approximate second acceleration Ax2' and the first acceleration Ax1 at each of a plurality of times. The distribution calculation section 15 may calculate a distribution of the acceleration A of the object 210 in the X-axis direction based on the plurality of second differences dx2.

[0079] The distribution calculation section 15 may similarly calculate the second difference dy2 for the first acceleration Ay1 and the second acceleration Ay2 in the Y-axis direction, and may similarly calculate the second difference dz2 for the first acceleration Az1 and the second acceleration Az2 in the Z-axis direction. The distribution calculation section 15 may similarly calculate the distribution of the acceleration A of the object 210 in the Y-axis direction based on the multiple second differences dy2, and may calculate the distribution of the acceleration A of the object 210 in the Z-axis direction based on the multiple second differences dz2.

[0080] The distribution calculation section 15 may calculate at least one of an approximate first acceleration Ax1' and an approximate second acceleration Ax2' based on the approximation line Lx. The distribution calculation section 15 may calculate the distribution of the acceleration A of the object 210 based on at least one of the first difference dx1 and the second difference dx2. The distribution calculation section 15 may calculate the distribution of the acceleration A of the object 210 based on at least one of a plurality of first differences dx1 and a plurality of second differences dx2.

[0081] Fig. 11 is a diagram showing an example of a distribution of a plurality of first differences dx1 across a plurality of times. In Fig. 11, the distribution is shown as a relationship between the first acceleration Ax1 and the first differences dx1. In Fig. 11, the distribution of the first differences dx1 calculated at 4000 times in the example of Fig. 6 is shown. In Fig. 11, the results of dividing each of the plurality of first differences dx1 by a common constant C may be plotted. The constant C is, for example, √2.

[0082] The positive maximum value of the multiple first differences dx1 is set as a maximum value Mx1, and the negative maximum value is set as a maximum value Mx1'. The resolution calculation section 17 may calculate at least one of the maximum value Mx1 and the maximum value Mx1'. The resolution calculation section 17 may calculate the resolution Rx in the X-axis direction of the second acceleration sensor 12 (see FIG. 5) based on at least one of the maximum value Mx1 and the maximum value Mx1'. The resolution calculation section 17 may calculate the resolution Rx by using at least one of the maximum value Mx1 and the maximum value Mx1' as the resolution Rx in the X-axis direction of the second acceleration sensor 12.

[0083] As described above, the first acceleration Ax1 and the second acceleration Ax2 ideally coincide with each other. Fig. 11 shows that the acceleration detected by the first acceleration sensor 11 (see Fig. 5) and the acceleration detected by the second acceleration sensor 12 (see Fig. 5) actually vary within the range between the maximum value Mx1 and the maximum value Mx1'. As described above, the first difference dx1 is the difference between the approximate first acceleration Ax1' and the second acceleration Ax2. Since the approximate first acceleration Ax1' is an acceleration approximated based on the approximation line Lx, at least one of the maximum value Mx1 and the maximum value Mx1' represents the resolution Rx of the second acceleration sensor 12.

[0084] Similarly, the positive maximum value of the multiple second differences dx2 is set as the maximum value Mx2, and the negative maximum value is set as the maximum value Mx2'. The resolution calculation section 17 may calculate at least one of the maximum value Mx2 and the maximum value Mx2'. The resolution calculation section 17 may calculate the resolution Rx of the first acceleration sensor 11 in the X-axis direction based on at least one of the maximum value Mx2 and the maximum value Mx2'. The resolution calculation section 17 may calculate the resolution Rx by using at least one of the maximum value Mx2 and the maximum value Mx2' as the resolution Rx of the first acceleration sensor 11 in the X-axis direction.

[0085] The resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 in the X-axis direction based on both the maximum value Mx1 and the maximum value Mx2. The resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 in the X-axis direction based on both the maximum value Mx1' and the maximum value Mx2'.

[0086] The resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of the multiple first differences dx1. In the example of Fig. 6, the resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of 4000 first differences dx1.

[0087] One of the multiple first differences dx1 may be extremely larger than the other first differences dx1. The first difference dx1 is a so-called outlier. Therefore, even if such a first difference dx1 is included, the resolution calculation unit 17 can easily calculate a more appropriate resolution Rx of the acceleration sensor 10 by calculating the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of the multiple first differences dx1.

[0088] The resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of the multiple second differences dx2. In the example of Fig. 6, the resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of 4000 second differences dx2. The resolution calculation section 17 may calculate the resolution Rx of the acceleration sensor 10 based on the standard deviation σx of the multiple first differences dx1 and the standard deviation σx of the multiple second differences dx2.

[0089] The resolution calculation unit 17 calculates the resolution R based on the correlation of the acceleration A detected by each of the multiple acceleration sensors 10, which are originally uncorrelated. Therefore, the sensor device 100 can calculate the limit at which the acceleration sensor 10 can detect the acceleration A.

[0090] Fig. 12 is a diagram showing an example of a distribution of a plurality of first differences dy1 across a plurality of times. In Fig. 12, the distribution is shown as a relationship between the first acceleration Ay1 and the first differences dy1. The maximum positive value of the plurality of first differences dy1 is set as a maximum value My1, and the maximum negative value is set as a maximum value My1'.

[0091] The resolution calculation section 17 may calculate at least one of the maximum value My1 and the maximum value My1'. The resolution calculation section 17 may calculate the resolution Ry in the Y-axis direction of the second acceleration sensor 12 (see FIG. 5) based on at least one of the maximum value My1 and the maximum value My1'. The resolution calculation section 17 may calculate the resolution Ry by using at least one of the maximum value My1 and the maximum value My1' as the resolution Ry in the Y-axis direction of the second acceleration sensor 12.

[0092] Similarly, the maximum positive value of the multiple second differences dy2 is set as the maximum value My2, and the maximum negative value is set as the maximum value My2'. The resolution calculation section 17 may calculate at least one of the maximum value My2 and the maximum value My2'. The resolution calculation section 17 may calculate the resolution Ry of the first acceleration sensor 11 in the Y-axis direction based on at least one of the maximum value My2 and the maximum value My2'. The resolution calculation section 17 may calculate the resolution Ry by using at least one of the maximum value My2 and the maximum value My2' as the resolution Ry of the first acceleration sensor 11 in the Y-axis direction.

[0093] The resolution calculation section 17 may calculate the resolution Ry of the acceleration sensor 10 based on the standard deviation σy of the multiple first differences dy1. In the example of FIG. 7, the resolution calculation section 17 may calculate the resolution Ry of the acceleration sensor 10 based on the standard deviation σy of 4000 first differences dy1. The resolution calculation section 17 may calculate the resolution Ry of the acceleration sensor 10 based on the standard deviation σy of the multiple second differences dy2. In the example of FIG. 7, the resolution calculation section 17 may calculate the resolution Ry of the acceleration sensor 10 based on the standard deviation σy of 4000 second differences dy2. The resolution calculation section 17 may calculate the resolution Ry of the acceleration sensor 10 based on the standard deviation σy of the multiple first differences dy1 and the standard deviation σy of the multiple second differences dy2.

[0094] Fig. 13 is a diagram showing an example of a distribution of a plurality of first differences dz1 across a plurality of times. In Fig. 13, the distribution is shown as a relationship between the first acceleration Az1 and the first differences dz1. The maximum positive value of the plurality of first differences dz1 is set as a maximum value Mz1, and the maximum negative value is set as a maximum value Mz1'.

[0095] The resolution calculation section 17 may calculate at least one of the maximum value Mz1 and the maximum value Mz1'. The resolution calculation section 17 may calculate the resolution Rz of the second acceleration sensor 12 (see FIG. 5) in the Z-axis direction based on at least one of the maximum value Mz1 and the maximum value Mz1'. The resolution calculation section 17 may calculate the resolution Rz by using at least one of the maximum value Mz1 and the maximum value Mz1' as the resolution Rz of the second acceleration sensor 12 in the Z-axis direction.

[0096] Similarly, the positive maximum value of the multiple second differences dz2 is set as the maximum value Mz2, and the negative maximum value is set as the maximum value Mz2'. The resolution calculation section 17 may calculate at least one of the maximum value Mz2 and the maximum value Mz2'. The resolution calculation section 17 may calculate the resolution Rz of the first acceleration sensor 11 in the Z-axis direction based on at least one of the maximum value Mz2 and the maximum value Mz2'. The resolution calculation section 17 may calculate the resolution Rz by using at least one of the maximum value Mz2 and the maximum value Mz2' as the resolution Rz of the first acceleration sensor 11 in the Z-axis direction.

[0097] The resolution calculation section 17 may calculate the resolution Rz of the acceleration sensor 10 based on the standard deviation σz of the multiple first differences dz1. In the example of FIG. 8, the resolution calculation section 17 may calculate the resolution Rz of the acceleration sensor 10 based on the standard deviation σz of 4000 first differences dz1. The resolution calculation section 17 may calculate the resolution Rz of the acceleration sensor 10 based on the standard deviation σz of the multiple second differences dz2. In the example of FIG. 8, the resolution calculation section 17 may calculate the resolution Rz of the acceleration sensor 10 based on the standard deviation σz of 4000 second differences dz2. The resolution calculation section 17 may calculate the resolution Rz of the acceleration sensor 10 based on the standard deviation σz of the multiple first differences dz1 and the standard deviation σz of the multiple second differences dz2.

[0098] 14 is a diagram showing an example of the relationship between time t and resolution Rx. Time ta is, for example, 9 p.m. Time tb is, for example, 8 a.m. The time until time ta is time Ta, the time from time ta to time tb is time Tb, and the time after time tb is time Tc. Time Ta and time Tc may be daytime times, and time Tb may be nighttime times.

[0099] As described above, in this example, one resolution Rx is calculated based on 4000 pieces of data detected over 20 seconds at a period T=5 ms. In this example, this one resolution Rx is calculated multiple times from before time ta to after time tb. Figure 14 shows the multiple resolutions Rx in relation to time t.

[0100] 15 is a diagram showing an example of the relationship between time t and standard deviation σx. When time Tb is nighttime and times Ta and Tc are daytime, the standard deviation σx at time Tb is likely to be smaller than the standard deviation σx at times Ta and Tc. However, even at time Tb, a peculiar behavior of the acceleration A as shown by the peak Px may be observed.

[0101] In the sensor device 100 of this example, the distribution calculation unit 15 calculates the distribution of the acceleration A based on the first acceleration Ax1 and the second acceleration Ax2, and the resolution calculation unit 17 calculates the resolution R of the acceleration sensor 10 based on the distribution of the acceleration A. Therefore, as can be seen from Fig. 14 and Fig. 15, even at the time when the behavior of the acceleration A indicated by the peak Px in the standard deviation σx is observed, the resolution Rx is unlikely to deteriorate.

[0102] Fig. 16 is a diagram showing an example of the relationship between time t and resolution Ry. Fig. 17 is a diagram showing an example of the relationship between time t and standard deviation σy. As in Fig. 15, in Fig. 17, a unique behavior of acceleration A indicated by a peak Py is observed at time Tb. In the sensor device 100 of this example, the resolution Ry is unlikely to deteriorate even at the time when the behavior of acceleration A indicated by a peak Py in standard deviation σy is observed.

[0103] Fig. 18 is a diagram showing an example of the relationship between time t and resolution Rz. Fig. 19 is a diagram showing an example of the relationship between time t and standard deviation σz. As in Fig. 15 and Fig. 17, in Fig. 19, a unique behavior of acceleration A indicated by a peak Pz is observed at time Tb. In the sensor device 100 of this example, the resolution Rz is unlikely to deteriorate even at the time when the behavior of acceleration A indicated by a peak Pz in standard deviation σz is observed.

[0104] Fig. 20 is a conceptual diagram showing another example of a method for calculating the distribution of the acceleration A. The difference between the first acceleration Ax1 and the second acceleration Ax2 is defined as a third difference dx. In this example, the distribution calculation unit 15 (see Fig. 5) calculates the distribution of the acceleration A of the object 210 based on the third difference dx. In Fig. 20, the third difference dx3 is indicated by a double-headed arrow. Note that although the approximation line Lx is shown in Fig. 20, in this example, the distribution calculation unit 15 calculates the distribution of the acceleration A without based on the approximation line Lx.

[0105] The distribution calculation section 15 (see FIG. 5) may calculate a distribution of the acceleration A of the object 210 based on a plurality of third differences dx3, which are third differences dx3 between the first acceleration Ax1 and the second acceleration Ax2 at each of a plurality of times. The plurality of times refers to 4000 times in the example of FIG. 6. The distribution calculation section 15 may calculate a distribution of the acceleration A of the object 210 in the X-axis direction based on the plurality of third differences dx3. The plurality of third differences dx3 refers to 4000 third differences dx3 in the example of FIG. 6.

[0106] The distribution calculation section 15 (see FIG. 5) may similarly calculate a third difference dy3 for the first acceleration Ay1 and the second acceleration Ay2 in the Y-axis direction, and may similarly calculate a third difference dz3 for the first acceleration Az1 and the second acceleration Az2 in the Z-axis direction. The distribution calculation section 15 may similarly calculate the distribution of the acceleration A of the object 210 based on the multiple third differences dy3, and may calculate the distribution of the acceleration A of the object 210 based on the multiple third differences dz3.

[0107] Fig. 21 is a diagram showing an example of a distribution of a plurality of third differences dx3 across a plurality of times. In Fig. 21, the distribution is shown as a relationship between the first acceleration Ax1 and the third differences dx3. In Fig. 21, the distribution of the third differences dx3 calculated at 4000 times in the example of Fig. 6 is shown.

[0108] The positive maximum value of the multiple third differences dx3 is set as a maximum value Mx3, and the negative maximum value is set as a maximum value Mx3'. The resolution calculation section 17 may calculate at least one of the maximum value Mx3 and the maximum value Mx3'. The resolution calculation section 17 may calculate a resolution Rx' in the X-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12 (see FIG. 5) based on at least one of the maximum value Mx3 and the maximum value Mx3'. The resolution calculation section 17 may calculate the resolution Rx' by setting at least one of the maximum value Mx3 and the maximum value Mx3' as the resolution Rx' in the X-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12.

[0109] As described above, the third difference dx3 is the difference between the first acceleration Ax1 and the second acceleration Ax2. Therefore, the resolution Rx′ represents the average of the resolution R in the X-axis direction of the first acceleration sensor 11 and the resolution R in the X-axis direction of the second acceleration sensor 12.

[0110] The resolution calculation section 17 may calculate the resolution Rx' of the acceleration sensor 10 based on the standard deviation σx' of the multiple third differences dx3. In the example of Fig. 6, the resolution calculation section 17 may calculate the resolution Rx' of the acceleration sensor 10 based on the standard deviation σx' of 4000 third differences dx3.

[0111] Fig. 22 is a diagram showing an example of a distribution of a plurality of third differences dy3 across a plurality of time points. In Fig. 22, the distribution is shown as a relationship between the first acceleration Ay1 and the third differences dy3. Fig. 22 shows the distribution of the third differences dy3 calculated at 4000 time points in the example of Fig. 7.

[0112] The positive maximum value of the multiple third differences dy3 is set as a maximum value My3, and the negative maximum value is set as a maximum value My3'. The resolution calculation section 17 may calculate at least one of the maximum value My3 and the maximum value My3'. The resolution calculation section 17 may calculate a resolution Ry' in the Y-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12 (see FIG. 5) based on at least one of the maximum value My3 and the maximum value My3'. The resolution calculation section 17 may calculate the resolution Ry' by using at least one of the maximum value My3 and the maximum value My3' as the resolution Ry' in the Y-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12.

[0113] The resolution calculation section 17 may calculate the resolution Ry' of the acceleration sensor 10 based on the standard deviation σy' of the multiple third differences dx3. In the example of Fig. 7, the resolution calculation section 17 may calculate the resolution Ry' of the acceleration sensor 10 based on the standard deviation σy' of 4000 third differences dy3.

[0114] Fig. 23 is a diagram showing an example of a distribution of a plurality of third differences dz3 across a plurality of time points. In Fig. 23, the distribution is shown as a relationship between the first acceleration Az1 and the third differences dz3. Fig. 23 shows the distribution of the third differences dy3 calculated at 4000 time points in the example of Fig. 8.

[0115] The positive maximum value of the multiple third differences dyz is set as a maximum value Mz3, and the negative maximum value is set as a maximum value Mz3'. The resolution calculation section 17 may calculate at least one of the maximum value Mz3 and the maximum value Mz3'. The resolution calculation section 17 may calculate a resolution Rz' in the Z-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12 (see FIG. 5) based on at least one of the maximum value Mz3 and the maximum value Mz3'. The resolution calculation section 17 may calculate the resolution Rz' by setting at least one of the maximum value Mz3 and the maximum value Mz3' as the resolution Rz' in the Z-axis direction of the first acceleration sensor 11 and the second acceleration sensor 12.

[0116] The resolution calculation section 17 may calculate the resolution Rz' of the acceleration sensor 10 based on the standard deviation σz' of the multiple third differences dz3. In the example of Fig. 8, the resolution calculation section 17 may calculate the resolution Rz' of the acceleration sensor 10 based on the standard deviation σz' of 4000 third differences dz3.

[0117] In the example shown in Fig. 5, the third acceleration sensor 13 may detect a third acceleration A3 of the object 210 at each of a plurality of times. The distribution calculation section 15 may calculate a first distribution of the acceleration A of the object 210 (see Fig. 1) based on the first acceleration and the second acceleration at each of a plurality of times. The first distribution is referred to as a first distribution D1. The first distribution D1 is the distribution of the first acceleration A1 and the second acceleration A2 shown in Figs. 6 to 8.

[0118] The distribution calculation section 15 may calculate a second distribution of the acceleration A of the object 210 (see FIG. 1) based on the second acceleration A2 and the third acceleration A3, similar to the first distribution D1. The second distribution is referred to as the second distribution D2. The distribution calculation section 15 may calculate a third distribution of the acceleration A of the object 210 (see FIG. 1) based on the third acceleration A3 and the first acceleration A1, similar to the first distribution. The third distribution is referred to as the third distribution D3.

[0119] The resolution calculation section 17 may calculate the resolution R of the first acceleration sensor 11, the second acceleration sensor 12, and the third acceleration sensor 13 based on the first distribution D1, the second distribution D2, and the third distribution D3. When the resolution calculation section 17 calculates the resolution R of the first acceleration sensor 11, the second acceleration sensor 12, and the third acceleration sensor 13 by the method shown in Figures 21 to 23 (when calculating the average resolution R of the three acceleration sensors 10), the resolution calculation section 17 calculates the resolution R based on the first distribution D1, the second distribution D2, and the third distribution D3, which makes it easier to calculate a more accurate resolution R than when the resolution R of the first acceleration sensor 11 and the second acceleration sensor 12 is calculated based only on the first distribution D1 (as in Figures 21 to 23).

[0120] The control unit 16 (see FIG. 5) may determine the acceleration sensor 10 having the lowest resolution R among the first acceleration sensor 11 to the third acceleration sensor 13 by comparing the magnitudes of the first distribution D1, the second distribution D2, and the third distribution D3. If the first acceleration sensor 11 to the third acceleration sensor 13 include an acceleration sensor 10 having a uniquely low resolution R due to, for example, a defect, the sensor device 100 can identify the acceleration sensor 10 having such resolution R. In this example, for example, if the first distribution and the third distribution D3 are uniquely larger than the second distribution D2, the control unit 16 can determine that the first acceleration sensor 11 is defective.

[0121] Similarly, the distribution calculation section 15 may calculate four or more distributions of the acceleration A for four or more acceleration sensors 10. The resolution calculation section 17 may calculate the resolution R of the four or more acceleration sensors 10 based on the four or more distributions for the four or more acceleration sensors 10.

[0122] 24 is a conceptual diagram showing the timing at which each of the multiple acceleration sensors 10 according to one embodiment of the present invention detects an acceleration A. In this example, a case will be described in which the multiple acceleration sensors 10 are a first acceleration sensor 11 and a second acceleration sensor 12 (see FIG. 5).

[0123] In this example, the first acceleration sensor 11 detects the first acceleration A1 at each of a plurality of times based on a first time tc1. The times ts1 and te1 are the first and last times of the plurality of times. In this example, the first acceleration sensor 11 detects the first acceleration A1 N times from the time ts1 to the time te1. In the examples of FIGS. 6 to 8, N is 4000. The first time tc1 may be the center time between the time ts1 and the time te1.

[0124] In this example, the second acceleration sensor 12 detects the second acceleration A2 at each of a plurality of times based on the second time tc2. The second time tc2 is different from the first time tc1. The times ts2 and te2 are the first and last times of the plurality of times, respectively. Note that the examples up to FIG. 23 are for the case where the first time tc1 and the second time tc2 are the same.

[0125] In this example, the distribution calculation unit 15 (see FIG. 5) calculates the distribution of the acceleration A of the object 210 (see FIG. 1) based on the first acceleration A1 at each of a plurality of times based on the first time tc and the second acceleration A2 at each of a plurality of times based on the second time tc2. In this example, the distribution calculation unit 15 calculates the distribution of the acceleration A, assuming that the times ts1 to te1 are the same as the times ts2 to te2, respectively.

[0126] 25 is a conceptual diagram showing a plurality of second times tc2. The distribution calculation unit 15 (see FIG. 5) may calculate a plurality of distributions of the acceleration A based on the first acceleration A1 at each of the plurality of times centered on the first time tc1 and the second acceleration A2 at each of the plurality of times centered on the plurality of second times tc2 (second times tc2-1 to tc2-n).

[0127] In this example, the distribution calculation unit 15 (see FIG. 5) calculates a first distribution Ds1 of the acceleration A based on a first acceleration A1 at each of a plurality of times based on a first time tc1 and a second acceleration A2 at each of a plurality of times based on a second time tc2-1. Similarly, the distribution calculation unit 15 calculates a second distribution Ds2 to an n-th distribution Dsn of the acceleration A.

[0128] The resolution calculation section 17 (see FIG. 5) may calculate the resolution R of the first acceleration sensor 11 and the second acceleration sensor 12 based on a plurality of distributions of the acceleration A. In this example, the resolution calculation section 17 calculates the resolution R of the first acceleration sensor 11 and the second acceleration sensor 12 based on the first distribution Ds1 to the n-th distribution Dsn.

[0129] Fig. 26 is a diagram showing an example of the relationship between the distribution of acceleration A and the resolution R. Fig. 26 plots the acceleration A and the resolution R for each of the first distribution Ds1 to the n-th distribution Dsn in Fig. 25. In Fig. 26, the second time tc2-h is a time between the second time tc2-1 and the second time tc-k, and the second time tc2-m is a time between the second time tc2-k and the second time tc-n.

[0130] The resolution calculation section 17 may calculate the minimum resolution Rmin of the first acceleration sensor 11 and the second acceleration sensor 12 based on a plurality of distributions (first distribution Ds1 to nth distribution Dsn). The smaller the difference between the first time tc1 and the second time tc2, the smaller the resolution R is likely to be. A smaller resolution R refers to an improvement in the resolution R. Based on a plurality of distributions (first distribution Ds1 to nth distribution Dsn), the resolution calculation section 17 can calculate the minimum resolution Rmin of the first acceleration sensor 11 and the second acceleration sensor 12.

[0131] As described above, the frequency oscillators 20 (see FIG. 2) in the multiple sensor units 200 (see FIG. 1) generate clock signals CK that are synchronized with each other. Therefore, the times based on the clock signal CK in the multiple sensor units 200 (in this example, the first time tc1 and the second time tc2) ideally coincide with each other. However, due to individual differences in the frequency oscillators 20, etc., the times in the multiple sensor units 200 may actually have errors. In this example, the resolution calculation unit 17 calculates the minimum resolution Rmin of the multiple acceleration sensors 10 based on the multiple distributions of the acceleration A. Therefore, even if there is an error in the times based on the clock signal CK in the multiple sensor units 200, the minimum resolution Rmin of the multiple acceleration sensors 10 can be calculated.

[0132] In this example, the user of the resolution measurement system 300 (see FIG. 1) may intentionally shift the time based on the clock signal CK in the second acceleration sensor 12 before or after the time based on the clock signal CK in the first acceleration sensor 11. This allows the user of the resolution measurement system 300 to know the minimum resolution Rmin.

[0133] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the claims that such modifications and improvements can also be included in the technical scope of the present invention.

[0134] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and may be realized in any order unless the output of a previous process is used in a later process. Even if the operational flow in the claims, specifications, and drawings is explained using "first," "next," etc. for convenience, it does not mean that it is essential to perform the process in this order. [Item 1] A plurality of acceleration sensors are provided on an object, the acceleration sensors being arranged within a predetermined distance from each other and configured to detect acceleration of the object; a distribution calculation unit that calculates a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, the distribution being an acceleration distribution of the object; a resolution calculation unit that calculates a resolution of the acceleration sensor based on the distribution of the plurality of accelerations calculated by the distribution calculation unit; A sensor device comprising: [Item 2] Each of the plurality of acceleration sensors has a movable electrode and fixed electrodes disposed adjacent to one side and the other side of the movable electrode in a predetermined direction, a direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in a first acceleration sensor among the plurality of acceleration sensors is the same as a direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in a second acceleration sensor among the plurality of acceleration sensors. Item 1. The sensor device according to item 1. [Item 3] the first acceleration sensor detects a first acceleration of the object at each of a plurality of times; the second acceleration sensor detects a second acceleration of the object at each of the plurality of times; the distribution calculation unit calculates a distribution of the acceleration of the object based on the first acceleration and the second acceleration at each of the plurality of times. Item 3. The sensor device according to item 2. [Item 4] The sensor device described in item 3, wherein the distribution calculation unit calculates an approximation line that represents a relationship between the first acceleration and the second acceleration over the multiple times, calculates at least one of an approximate first acceleration in which the first acceleration is approximated and an approximate second acceleration in which the second acceleration is approximated based on the approximation line, and calculates a distribution of the acceleration of the object based on at least one of a first difference between the approximate first acceleration and the second acceleration and a second difference between the approximate second acceleration and the first acceleration. [Item 5] The sensor device described in item 4, wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on at least one of a plurality of first differences, the first differences being between the approximate first acceleration and the second acceleration at each of the plurality of times, and a plurality of second differences, the second differences being between the approximate second acceleration and the first acceleration at each of the plurality of times. [Item 6] 6. The sensor device according to item 5, wherein the resolution calculation section calculates the resolution of the second acceleration sensor based on a maximum value of the plurality of first differences. [Item 7] 7. The sensor device according to item 5 or 6, wherein the resolution calculation unit calculates the resolution of the first acceleration sensor based on a maximum value of the plurality of second differences. [Item 8] 6. The sensor device according to item 5, wherein the resolution calculation unit calculates a resolution of the acceleration sensor based on a standard deviation of the plurality of first differences. [Item 9] 7. The sensor device according to item 5 or 6, wherein the resolution calculation unit calculates a resolution of the acceleration sensor based on a standard deviation of the plurality of second differences. [Item 10] 4. The sensor device according to item 3, wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on a third difference which is a difference between the first acceleration and the second acceleration. [Item 11] Item 11. The sensor device according to item 10, wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on a plurality of third differences between the first acceleration and the second acceleration at each of the plurality of times. [Item 12] Item 12. The sensor device according to item 11, wherein the resolution calculation unit calculates the resolution of the first acceleration sensor and the second acceleration sensor based on a maximum value of the multiple third differences. [Item 13] Item 12. The sensor device according to item 11, wherein the resolution calculation unit calculates the resolution of the first acceleration sensor and the second acceleration sensor based on a standard deviation of the multiple third differences. [Item 14] a third acceleration sensor among the plurality of acceleration sensors detects a third acceleration of the object at each of the plurality of times; the distribution calculation unit calculates, at each of the plurality of times, a first distribution of acceleration of the object based on the first acceleration and the second acceleration, calculates a second distribution of acceleration of the object based on the second acceleration and the third acceleration, and calculates a third distribution of acceleration of the object based on the third acceleration and the first acceleration; the resolution calculation unit calculates resolutions of the first acceleration sensor, the second acceleration sensor, and the third acceleration sensor based on the first distribution, the second distribution, and the third distribution. 13. A sensor device according to any one of items 3 to 12. [Item 15] the first acceleration sensor detects a first acceleration of the object at each of a plurality of times based on a first time; the second acceleration sensor detects a second acceleration of the object at each of a plurality of times based on one or a plurality of second times different from the first time; the distribution calculation unit calculates a distribution of acceleration of the object based on the first acceleration at each of the plurality of times relative to the first time and the second acceleration at each of the plurality of times relative to the second time. Item 3. The sensor device according to item 2. [Item 16] the distribution calculation unit calculates a plurality of distributions of acceleration of the object based on the first acceleration at each of the plurality of times relative to the first time and the second acceleration at each of the plurality of times relative to the plurality of second times; the resolution calculation unit calculates the resolutions of the first acceleration sensor and the second acceleration sensor based on the plurality of distributions. Item 16. The sensor device according to item 15. [Item 17] Item 17. The sensor device according to item 16, wherein the resolution calculation unit calculates a minimum resolution of the first acceleration sensor and the second acceleration sensor based on the multiple distributions. [Explanation of symbols]

[0135] 10 acceleration sensor, 11 first acceleration sensor, 12 second acceleration sensor, 13 third acceleration sensor, 14 fourth acceleration sensor, 15 distribution calculation section, 16 control section, 17 resolution calculation section, 20 frequency oscillator, 21 fixed electrode, 22 fixed electrode, 23 movable electrode, 24 fixed frame, 25 elastic section, 26 fixed electrode, 27 space, 30 cell sensor control unit, 50...analog signal processing unit, 52...LPF, 54...AD converter, 58...interface unit, 70...storage unit, 90...voltage application unit, 92...charge amplifier, 100...sensor device, 110...computer, 130...power supply hub, 140...NTP server, 150...communication line, 200...sensor unit, 210...object, 300...resolution measurement system

Claims

1. A plurality of acceleration sensors are provided on an object, the acceleration sensors being arranged within a predetermined distance from each other and configured to detect acceleration of the object; a distribution calculation unit that calculates a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, the distribution being an acceleration distribution of the object; a resolution calculation unit that calculates a resolution of the acceleration sensor based on the distribution of the plurality of accelerations calculated by the distribution calculation unit; Equipped with a first acceleration sensor among the plurality of acceleration sensors detects a first first acceleration and a second first acceleration of the object at a first time and a second time among a plurality of times, respectively; a second acceleration sensor among the plurality of acceleration sensors detects a first second acceleration and a second second acceleration of the object at the first time and the second time, respectively; the distribution calculation unit calculates a distribution of acceleration of the object based on the first first acceleration, the second first acceleration, the first second acceleration, and the second second acceleration; Sensor device.

2. The sensor device of claim 1, wherein the distribution calculation unit calculates the distribution of the acceleration of the object based on the relationship across the multiple times between a first acceleration of the object at each of the multiple times and a second acceleration of the object at each of the multiple times.

3. The sensor device described in claim 2, wherein the distribution calculation unit calculates an approximation line representing the relationship between the first acceleration of the object and the second acceleration of the object over the multiple times, calculates an approximate first acceleration that approximates the first acceleration based on the approximation line, and calculates a distribution of the acceleration of the object based on the approximate first acceleration and the second acceleration.

4. The sensor device described in Claim 3, wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on a first difference between the approximate first acceleration and the second acceleration.

5. The sensor device according to claim 4 , wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on a plurality of first differences, the first differences being between the approximate first acceleration and the second acceleration at each of the plurality of times.

6. The sensor device according to claim 5 , wherein the resolution calculation section calculates the resolution of the second acceleration sensor based on a maximum value of the plurality of first differences.

7. The sensor device according to claim 5 , wherein the resolution calculation section calculates the resolution of the acceleration sensor based on a standard deviation of the plurality of first differences.

8. A plurality of acceleration sensors are provided on an object, the acceleration sensors being arranged within a predetermined distance from each other and detecting the acceleration of the object; a distribution calculation unit that calculates a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, the distribution being an acceleration distribution of the object; a resolution calculation unit that calculates a resolution of the acceleration sensor based on the distribution of the plurality of accelerations calculated by the distribution calculation unit; Equipped with a first acceleration sensor among the plurality of acceleration sensors detects a first acceleration of the object at each of a plurality of times; a second acceleration sensor among the plurality of acceleration sensors detects a second acceleration of the object at each of the plurality of times; The distribution calculation unit calculates a distribution of the acceleration of the object based on a third difference which is a difference between the first acceleration and the second acceleration. Sensor device.

9. The sensor device according to claim 8 , wherein the distribution calculation unit calculates a distribution of the acceleration of the object based on a plurality of third differences, the third differences being between the first acceleration and the second acceleration at each of the plurality of times.

10. The sensor device according to claim 9 , wherein the resolution calculation section calculates the resolution of the first acceleration sensor and the second acceleration sensor based on a maximum value of the plurality of third differences.

11. The sensor device according to claim 9 , wherein the resolution calculation section calculates the resolution of the first acceleration sensor and the second acceleration sensor based on a standard deviation of the plurality of third differences.

12. A plurality of acceleration sensors are provided on an object, the acceleration sensors being arranged within a predetermined distance from each other and detecting the acceleration of the object; a distribution calculation unit that calculates a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, the distribution being an acceleration distribution of the object; a resolution calculation unit that calculates a resolution of the acceleration sensor based on the distribution of the plurality of accelerations calculated by the distribution calculation unit; Equipped with a first acceleration sensor among the plurality of acceleration sensors detects a first acceleration of the object at each of a plurality of times; a second acceleration sensor among the plurality of acceleration sensors detects a second acceleration of the object at each of the plurality of times; a third acceleration sensor among the plurality of acceleration sensors detects a third acceleration of the object at each of the plurality of times; the distribution calculation unit calculates, at each of the plurality of times, a first distribution of acceleration of the object based on the first acceleration and the second acceleration, calculates a second distribution of acceleration of the object based on the second acceleration and the third acceleration, and calculates a third distribution of acceleration of the object based on the third acceleration and the first acceleration; the resolution calculation unit calculates resolutions of the first acceleration sensor, the second acceleration sensor, and the third acceleration sensor based on the first distribution, the second distribution, and the third distribution. Sensor device.

13. A plurality of acceleration sensors are provided on an object, the acceleration sensors being arranged within a predetermined distance from each other and detecting the acceleration of the object; a distribution calculation unit that calculates a distribution of a plurality of accelerations detected by the plurality of acceleration sensors, the distribution being an acceleration distribution of the object; a resolution calculation unit that calculates a resolution of the acceleration sensor based on the distribution of the plurality of accelerations calculated by the distribution calculation unit; Equipped with a first acceleration sensor among the plurality of acceleration sensors detects a first acceleration of the object at each of a plurality of times based on a first time; a second acceleration sensor of the plurality of acceleration sensors detects a second acceleration of the object at each of a plurality of times based on one or a plurality of second times different from the first time; the distribution calculation unit calculates a distribution of acceleration of the object based on the first acceleration at each of the plurality of times relative to the first time and the second acceleration at each of the plurality of times relative to the second time; Sensor device.

14. the distribution calculation unit calculates a plurality of distributions of acceleration of the object based on the first acceleration at each of the plurality of times relative to the first time and the second acceleration at each of the plurality of times relative to the plurality of second times; the resolution calculation unit calculates the resolutions of the first acceleration sensor and the second acceleration sensor based on the plurality of distributions. The sensor device according to claim 13.

15. The sensor device according to claim 14 , wherein the resolution calculation section calculates the minimum resolution of the first acceleration sensor and the second acceleration sensor based on the plurality of distributions.

16. Each of the plurality of acceleration sensors has a movable electrode and fixed electrodes disposed adjacent to one side and the other side of the movable electrode in a predetermined direction, a direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in the first acceleration sensor is the same as a direction from the fixed electrode arranged on one side of the movable electrode to the fixed electrode arranged on the other side in the second acceleration sensor. A sensor device according to any one of claims 1 to 15.

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